I recently switched from Masonry to Sections.
I am using some vertical stacks and noticed that the dashboard is leaving gaps (on the middle right there).
Is there a way to fix this, apart from splitting up the vertical stacks?
Nope, this is by design for sections. Sections need to be approx the same hight if you want to avoid gaps to the row below.
I would like a masonry-style sections type dashboard, but that isn't available. So I stick with custom grid and don't use sections for now. I have too much smart stuff (10 pretty full tabs) to waste this much space 
Don't use two section on the right. Drag and drop the card that is down the bottom (in its own section) into the top section.
